Refrigeration systems performing refrigeration cycles by circulating refrigerants are conventionally widely used for air conditioners. Examples of such air conditioners include a multi-type air conditioner in which a plurality of indoor units are connected in parallel to each other and each of the indoor units is connected in parallel to an outdoor unit.
For example, an air conditioner proposed in Patent Document 1 includes: an outdoor unit including a compressor, an outdoor heat exchanger (i.e., a heat-source side heat exchanger) and an outdoor expansion valve; and two indoor units each including an indoor heat exchanger (i.e., an application side heat exchanger). Two branch pipes respectively connected to the two indoor heat exchangers have indoor expansion valves of the indoor heat exchangers. The indoor refrigeration capability of this air conditioner in heating operation is controlled by adjusting the opening degree of the indoor expansion valve based on the degree of supercooling by each of the indoor heat exchangers.